drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers

Summary

In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers Three sideband reply parsers read 16-bit fields as: val = (raw->msg[idx] << 8) | (raw->msg[idx+1]); and check bounds only after the fact. When idx == raw->curlen, raw->msg[idx+1] reads one byte past the received message data into the following struct fields (curchunk_len, curchunk_idx, curlen). Affected functions: • drm_dp_sideband_parse_enum_path_resources_ack() full_payload_bw_number and avail_payload_bw_number fields • drm_dp_sideband_parse_allocate_payload_ack() allocated_pbn field • drm_dp_sideband_parse_query_payload_ack() allocated_pbn field Fix by using a single combined check (idx + 2 > curlen) before each 2-byte read. Since the check is strictly tighter than idx > curlen, no separate step is needed. [added fixes tag]

Timeline

1. Aug 10, 2026, 12:01 PM UTCCVE published
2. Aug 23, 2026, 12:46 PM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  3.17

References 8